Have I done something wrong? Not sure why my post is the only one without any response?
The site seems to have been down for some time today, reason unknown. I'm just looking at your case at 22.35. Please also note, everybody on here is acting pro-bono, (unpaid), so have to do the day job to make a living, except for me who is retired, and even I must obey the Oberkommanderin der Wehrmacht !
The sign where you parked, (shown in your GSV link) specifically allows BB holders 3 hours parking, but only between the times specified. You were outside those times. Did you read the sign before parking-up and walking off ?
Unfortunately, your reps were based on mitigation which TfL have decided not to accept. If you take the case to London Tribunals, they cannot accept mitigation, so you'd lose, unless you have another argument to present.
There may be a 'technical' appeal argument at LT based on TfL's management of the enforcement process, so wait a bit to see what comes up, but don't miss the deadline in their letter of rejection (pay or appeal).